Inadequate physical activity may boost genetic risk of obesity

Researchers have found that low levels of physical activity and inefficient sleep patterns may intensify the effects of genetic risk factors for obesity.

"We wanted to find out if obesity-related genes and activity level have an interactive effect on obesity risk - if there is a 'double whammy' effect of being both at genetic risk and physically inactive beyond the additive effect of these factors," said the study's lead author Andrew Wood, a researcher at the University of Exeter Medical School.

The new study made use of wrist accelerometer data and a large genetic dataset from about 85,000 UK Biobank participants aged 40 to 70.

The researchers computed a genetic risk score for each participant based on 76 common variants known to be associated with elevated risk of obesity and analyzed this score in the context of accelerometer data and participants' BMIs.

They found the strongest evidence to date of a modest gene-activity interaction. 

For example, for a person of average height with 10 genetic variants associated with obesity, the genetic risk accounted for a 3.6 kg increase in weight among those who were less physically active but just 2.8 kg among those who were more active. 

The results were similar in analyses of sleep patterns. Among the participants with some genetic risk of obesity, those who woke up frequently or slept more restlessly had higher BMIs than those who slept more efficiently.

The results of the study was presented at the American Society of Human Genetics (ASHG) 2017 annual meeting in Orlando.

"We hope these findings will inform clinicians who help people lose or maintain their weight and contribute to the understanding that obesity is complex and its prevention may look different for different people," said Timothy Frayling, Professor at the University of Exeter Medical School.